EP0592173A1 - Gasdurchflusssensor - Google Patents

Gasdurchflusssensor Download PDF

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Publication number
EP0592173A1
EP0592173A1 EP93307871A EP93307871A EP0592173A1 EP 0592173 A1 EP0592173 A1 EP 0592173A1 EP 93307871 A EP93307871 A EP 93307871A EP 93307871 A EP93307871 A EP 93307871A EP 0592173 A1 EP0592173 A1 EP 0592173A1
Authority
EP
European Patent Office
Prior art keywords
electrode
gas flow
base
air flow
flow sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93307871A
Other languages
English (en)
French (fr)
Inventor
Takahisa Yamashita
Yasushi Hibino
Hikari Tsuchiya
Osami Kushida
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Texas Instruments Inc
Original Assignee
Texas Instruments Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Texas Instruments Inc filed Critical Texas Instruments Inc
Publication of EP0592173A1 publication Critical patent/EP0592173A1/de
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/02—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer
    • G01P5/04—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring forces exerted by the fluid on solid bodies, e.g. anemometer using deflection of baffle-plates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/20—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow
    • G01F1/28—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow by drag-force, e.g. vane type or impact flowmeter

Definitions

  • This invention relates generally to gas flow sensors and more particularly to a gas flow sensor for the measurement of gas flow in an electronically controlled fuel injection system of a motor vehicle by way of example.
  • FIG. 1 Three types of conventional air or gas flow sensors described below are arranged at a location indicated at (a) in Fig. 1 in an electronically controlled fuel injection system 40 in order to measure the flow of air that flows inside electrically controlled fuel injection system 40.
  • a first conventional air flow sensor 70 of the "Bayne type" is shown in Fig. 2.
  • An air flow sensor of the Bayne type measures the flow of the air by reading the angle of wing 71 that is produced by the flow of air indicated by arrow (c) by means of a potentiometer 72.
  • Problems associated with this type of sensor include the fact that the potentiometer 72 has an electrical contact which results in a problem regarding durability. Further, where there are pulsations in the air current, there is a problem in that the action does not stabilize. Since it is necessary to arrange wing 71 in the air current, there is also a problem in that the pressure loss at this part becomes large.
  • An air flow sensor 80 of the hot wire type is shown in Fig. 3.
  • An air flow sensor 80 of the hot wire type measures the flow of air utilizing the change in resistance value of the wire based on the cooling effect.
  • Problems with this type of sensor include the fact that extremely fine platinum resistance wire 81 is used in such sensors and dust, etc. tends to adhere to its surface, with a consequence that the output signal tends to become unstable. There is an added problem in that the sensor tends to be affected by pulsation as it is too sensitive to the variations in the air flow.
  • An air flow sensor 90 of the "Carman Boltex" type is shown in Fig. 4.
  • An air flow sensor 90 of the Carman Boltex type places a wedge-shaped member 91 as shown in the drawing in an air current and counts the Carman vortexes that are generated, thereby measuring the air flow.
  • Methods for counting the Carman vortexes utilize supersonic waves and light. Problems with this type of sensor include the fact that such sensors tend to be affected by pulsations of the air current at a time when the Carman vortexes are counted, with no accurate measurement being carried out at the location where this pulsation exists.
  • pulsesation of the air current means the variations in the air current that are generated due to the opening or closing of the intake valve 42.
  • Fig. 5 indicates on the same graph the degree of accelerator opening (d) and the output signal of the air flow sensor (e) by installing an air flow sensor 80 of the hot wire type at a location shown in Fig. 1 at (a).
  • Fig. 6 indicates on the same graph the degree of accelerator opening (f) and the output of the air flow volume sensor (g) by installing an air flow volume sensor 80 of the hot wire type at a location which is closer to the combustion chamber 41 than the position indicated in Fig. 1 at (a).
  • FIG. 5 A comparison between Figs. 5 and 6 reveals the fact that, in the case where the air flow sensor 80 of the hot wire type is located closer to the combustion 41 than the location indicated in Fig. 1 at (a), the output signal of the air flow sensor is affected by the intake pulsation, thereby becoming extremely unstable.
  • a gas flow sensor made according to this invention comprises a base having an anterior face portion that receives pressure in conformance with gas flow that is to be measured and having a posterior configuration which results in the sensor being unaffected by back pressure, the first electrode being cantilever mounted in such a way as to receive the pressure at the anterior portion of the base which deflects in conformance with the pressure level.
  • the second electrode is mounted in the base with a prescribed gap from the first electrode and in a manner so that it is not deflected by the pressure.
  • the capacitance between the first and second electrodes in the electronically controlled fuel injection system changes in conformance with the amount of flow of the air current. This capacitance is detected and is outputted as a measure of air current flow.
  • a strain detection element is disposed between a first cantilever, flexible electrode and a support electrode.
  • the pressure placed on this element changes in conformance with the flow of the air current to which the cantilever is subjected.
  • the strain detection element produces a voltage corresponding to this pressure. This electric voltage is detected and is outputted as an air flow measure.
  • a back pressure deflecting member is attached to the free distal end of the cantilever electrode to deflect reverse pulses of air in the same manner as the posterior body portion of the first embodiment.
  • Figs. 7-9B show an air flow sensor identified by numeral 1 made in accordance with a first embodiment of the invention.
  • Air flow sensor 1 disposed in an electronically controlled fuel injection system as shown in Fig. 1 (such as a mass-flow type fuel injection system), is subjected to its air flow (intake) with the first electrode 11 that is formed of a cantilever mounted, electrically conductive flexible member, being deflected by the pressure of the intake flow, as a result of which the gap from the second electrode 12 changes and the change in capacitance is utilized for a measurement of the air flow volume.
  • Electrodes 11 and 12 generally aligned with each other and co-extensive in length, in effect form capacitor plates of a variable capacitor.
  • the first electrode 11 is cantilever supported by a body 13 at the anterior face portion thereof and at a prescribed distance from and in opposition to a second electrode 12 so that it possesses a capacitance vis-a-vis the second electrode 12.
  • the second electrode 12 is supported on the back wall of a recess formed in body 13 so that it does not deflect when the sensor is subjected to air flow.
  • the first electrode 11 extends in a direction which is parallel to the direction in which the second electrode 12 extends as shown in Fig. 8A in the at rest position where no air flow is being received. Electrode 11 is relatively thin having opposed front and back faces having relatively large surface areas with the outer face serving as a flow sensor. When air flow occurs electrode 11 is deflected as shown in Fig. 8B, as a result of which the gap vis-a-vis the second electrode 12 is reduced and capacitance is increased.
  • Body 13 composed of any suitable electrically insulating member has a screw thread formed at one end at 13.1 which is adapted to be inserted into a hole for the air flow sensor installation of the electronically controlled fuel injection system 40 and is mounted to the electronically controlled fuel injection system 40 by means of a nut 14.
  • An outwardly extending flange 13.2 is provided at the lower part of the screw thread of body 13 and this flange cooperates with the screw thread for the sensor installation of the electronically controlled fuel injection system 40 and, since it is constructed in such a way as to maintain the air-tightness or seal of the electronically controlled fuel injection system 40, air flow sensor 1 can be securely mounted and tightly sealed in the electronically controlled fuel injection system 40.
  • the air seal may further be improved by using a rubber packing or the like.
  • the posterior (pulsation receiving part) of body 13 is configured having a smooth curved surface.
  • This streamlined surface shown, for example, by (h) in Fig. 9A, is arranged facing the combustion chamber 41 and the intake valve 42 (Fig. 1) of the electronically controlled fuel injection system 40. Because of this, the intake pulsation from the intake valve 42 flows in the direction indicated by an arrow (i) in Figs. 9A and 9B and does not affect the first electrode 11.
  • Electric wires 15a and 15b are connected to the first electrode 11 and the second electrode 12, respectively for transmitting the output signals.
  • the capacitance detection circuit 31 is a circuit that detects the capacitance between the first electrode 11 and the second electrode 12 of the first air flow sensor 1 on the basis of the capacitance information that is outputted from the first air flow sensor 1 through the electric wires 15a and 15b and the output signal that comes from an oscillation circuit 51 and a switching circuit 52 and that inputs same in the filter circuit 32.
  • the filter circuit 32 is a circuit that filters the output of the capacitance detection circuit 31, removes the noise portion and outputs same at the buffer circuit 33.
  • the buffer circuit 33 is a circuit that buffers the output of the filter circuit 32 and outputs same from the electrostatic detection device 30 as a measurement of air flow.
  • the air flow sensor 1 is mounted in the electronically controlled fuel injection system 40 by a nut 14 at a location which is shown in Fig. 1 at (b) in accordance with the aforementioned method.
  • That location is a location where the intake pulsation from the intake valve 42 is large. However, it flows to the side because of the shape of the posterior portion of body 13 and does not affect the first electrode 11.
  • This capacitance is detected by the capacitance detection device 30 and is outputted as a measurement of air flow in the electronically controlled fuel injection system 40.
  • This air flow information is used as a parameter for fuel injection control in a control circuit (which is not shown in the drawings) of the electronically controlled fuel injection system 40.
  • Air flow sensor 1 can be placed at a location indicated in Fig. 1 at (b) of the electronically controlled fuel injection system 40 where the conventional air flow volume sensor could not be placed due to the construction which has been described above.
  • the body 13 has such a configuration as has been described above and as the posterior portion of the sensor is arranged in the electronically controlled fuel injection system 40 in such a way as to face the side of the intake valve 42, air flow sensor 1 is insensitive to intake pulsation.
  • air flow sensor 1 is insensitive to the effect of dust, etc. because of the absence of any contact, its accuracy is high and it is durable.
  • air flow sensor 1 can be made smaller in size and lighter in weight than the conventional air flow sensor. Because of this, there will be fewer restrictions upon the placement of the electronically controlled fuel injection system 40.
  • Air flow sensor 2 employs a strain detection element 24 such as a piezoelectric element that has been placed between a cantilever mounted electrode 21 and a support electrode 22.
  • Cantilever mounted electrode 21 comprises an electrically conductive flexible member, supported by a body 23, mounted facing support electrode 22 by sandwiching strain detection element 24 therebetween. A pressure dependent upon air flow is exerted on strain detection element 24.
  • the cantilever mounted electrode 21 extends in a direction parallel with the direction in which the support electrode 22 extends as shown in Fig. 12A in the at rest condition, in the absence of an air current. In the case where there is an air flow, however, it is deflected as shown in Fig. 12B, as a result of which the distance from the support electrode 22 is narrowed and the pressure that is applied to the strain detection element 24 is increased.
  • Body 23 is composed of an electrically insulating material and supports the cantilever electrode 21 which extends away from body 23 to a free distal end and the support electrode 22 which is essentially disposed completely within body 23.
  • a screw thread 23.1 is provided at one end of body 23 and an outwardly extending flange 23.2 is provided at the lower part of the screw groove of body 23.
  • Screw thread 23.1 and flange 23.2 are for the purpose of mounting air flow sensor 2 in the electronically controlled fuel injection system 40.
  • the method of mounting the sensor is the same as was explained in connection with body 13 of sensor 1 of the first embodiment.
  • Strain detection element 24 is arranged between the cantilever electrode 21 and the support electrode 22 and outputs a voltage corresponding to the pressure that is applied by the deflection of the cantilever electrode 21.
  • Deflecting member 25 reduces the effect of the intake pulsation upon the cantilever mounted electrode in a manner similar to the pulsation receiving portion of body 13 of air flow sensor 1. Although pulsation received on member 25 will have some minimal tendency to deflect electrode 21, such tendency is greatly reduced by the streamline posterior surface.
  • Air flow volume sensor 2 is mounted to the electronically controlled fuel injection system 40 with the posterior portion of back pressure deflection member 25 facing the side of the combustion chamber 41. Because of this, the intake pulsation from the intake valve 42 flows in the direction indicated by (i) in Fig. 11 and has minimal affect on the cantilever mounted electrode 21.
  • air current from the air cleaner 42 flows in the direction which is indicated by (k) in Fig. 11 and impinges directly upon cantilever mounted electrode 21 and accurately deforms the cantilever mounted electrode 21.
  • Electric wires 26a and 26b are connected to the cantilever mounted electrode 21 and the support electrode 22 respectively and transmit the output signal.
  • Air flow sensor 2 is fixed by a nut 14 at a location which is shown in Fig. 1 at (b) by the aforementioned method in the electronically controlled fuel injection system 40.
  • this location is a location where the intake pulsation from the intake valve 42 is large.
  • the intake pulsation flows to the side due to the shape of the back pressure deflection member 25 and does not materially affect the cantilever mounted electrode 21.
  • This output voltage is used as a measure of air flow in the electronically controlled fuel injection system 40.
  • This air flow information is used as a parameter for fuel injection control in the electronically controlled fuel injection system 40.
  • air flow sensor 2 By constructing air flow sensor 2 in this manner, it becomes possible to obtain an effect which is similar to that which is obtained from air flow volume sensor 1 as explained in connection with the first embodiment.
  • gas flow sensor according to this invention can be used in the flow measurement of various gases such as oxygen, nitrogen, etc. in addition to the measurement of the air flow volume as described in the aforementioned example.
  • the gas flow sensor according to this invention can assume various constructions other than those described in various examples above.
  • the various examples described above are merely exemplary.
  • the air flow volume sensor of this invention is insensitive to the effect of dust, etc. because of the absence of any contacts, its accuracy is high, it is insensitive to the effects of intake pulsation, it is high durable, can be set up at a location where the response can be quick in the neighborhood of the combustion chamber in the electronically controlled fuel injection system and, by solving the problem that arises in the transitional control of the engine combustion, it can prevent any worsening of the exhaust gas.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Measuring Volume Flow (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
EP93307871A 1992-10-07 1993-10-04 Gasdurchflusssensor Withdrawn EP0592173A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP4293850A JPH06117890A (ja) 1992-10-07 1992-10-07 気体流量センサ
JP293850/92 1992-10-07

Publications (1)

Publication Number Publication Date
EP0592173A1 true EP0592173A1 (de) 1994-04-13

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ID=17799971

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93307871A Withdrawn EP0592173A1 (de) 1992-10-07 1993-10-04 Gasdurchflusssensor

Country Status (4)

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EP (1) EP0592173A1 (de)
JP (1) JPH06117890A (de)
KR (1) KR940009667A (de)
AU (1) AU4872293A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10420374B2 (en) 2009-09-18 2019-09-24 Altria Client Services Llc Electronic smoke apparatus
CN111289768A (zh) * 2020-03-25 2020-06-16 南京管科智能科技有限公司 一种柔性电子水尺及采用该水尺测流速的方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9072321B2 (en) * 2009-09-18 2015-07-07 Minilogic Device Corporation Ltd. Electronic smoke

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH501215A (fr) * 1968-05-27 1970-12-31 Eastech Débitmètre
DD124440A1 (de) * 1976-03-05 1977-02-23 Dieter Troppens Messwertaufnehmer fuer gasvolumenstrom
DE2802830A1 (de) * 1978-01-23 1979-07-26 Gerhard Dr Ing Mueller Fluid-stroemungsmesser
DE2926811A1 (de) * 1979-07-03 1981-01-22 Malmedie & Co Maschf Durchflussmesseinrichtung
DD293654A5 (de) * 1990-04-11 1991-09-05 Adw Institut Fuer Meereskunde,De Sensor zur messung des gradienten der stroemungsgeschwindigkeit in marinen und limnischen gewaessern

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH501215A (fr) * 1968-05-27 1970-12-31 Eastech Débitmètre
DD124440A1 (de) * 1976-03-05 1977-02-23 Dieter Troppens Messwertaufnehmer fuer gasvolumenstrom
DE2802830A1 (de) * 1978-01-23 1979-07-26 Gerhard Dr Ing Mueller Fluid-stroemungsmesser
DE2926811A1 (de) * 1979-07-03 1981-01-22 Malmedie & Co Maschf Durchflussmesseinrichtung
DD293654A5 (de) * 1990-04-11 1991-09-05 Adw Institut Fuer Meereskunde,De Sensor zur messung des gradienten der stroemungsgeschwindigkeit in marinen und limnischen gewaessern

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10420374B2 (en) 2009-09-18 2019-09-24 Altria Client Services Llc Electronic smoke apparatus
US11974610B2 (en) 2009-09-18 2024-05-07 Altria Client Services Llc Electronic smoke apparatus
CN111289768A (zh) * 2020-03-25 2020-06-16 南京管科智能科技有限公司 一种柔性电子水尺及采用该水尺测流速的方法

Also Published As

Publication number Publication date
JPH06117890A (ja) 1994-04-28
AU4872293A (en) 1994-04-21
KR940009667A (ko) 1994-05-20

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